U.S. Pat. No. 3,755,899, which issued to the present inventor, and which is assigned to the present assignee, discloses and claims a similar type of control unit. The control unit of the patent includes an over-center spring coupled to each of a number of pivotally mounted arms, with the hanpieces being respectively supported by the arms, and it requires that the arms themselves be flipped to the up positions after the handpieces have been removed to initiate the flow of air and/or water to the handpieces.
U.S. Pat. No. 4,117,861, which also issued to the present inventor, and which also is assigned to the present assignee, discloses a slightly different type of control unit in which the handpieces actuate corresponding pinch valve members directly as they are inserted into the holders. In the control unit of the present invention, like the control unit of the latter patent, positive valving action is obtained merely by inserting the handpiece into its holder, and by withdrawing the handpiece from the holder. This patent also discloses how pressure in a selected flow path may also inflate a "swell tube" which, in turn, operates other pinch valves.
As stated in the two patents referred to in the preceding paragraph, it is the usual practice in present-day dental offices to use a plurality of separate handpieces which are driven at high speeds by compressed air. In many instances, as mentioned above, the high speed handpieces also direct a stream of fluid, usually air or water, as a coolant into the drilled area of the tooth being treated.
It is also common practice in the prior art for each of the dental handpieces to be removably supported on individual holders which, in turn, are mounted on a console adjacent to the dental chair. Compressed air and pressurized water are supplied to the various handpieces in the prior art equipment through individual tubes. The air and water are obtained from the usual mains, and these fluids are usually supplied to the console through foot operated valves.
In the prior art, additional valves are provided in the console so that the flow of the pressurized air and water to the individual handpieces may be controlled. With such equipment, the dentist causes the air and water to be supplied to the console by actuating his foot operated valve, and he then causes air or water, or both, to be supplied to a selected handpiece, by actuating appropriate valves in the console.
However, the prior art console valving, in addition to being more expensive than the control unit of the invention, uses pistons with "O" ring or diaphragms and other such seals and actuators usually in complicated sequences of pilot operation to open a passageway to the selected handpiece. The present invention uses only simple mechanical linkage and direct action to pinch tubings, eliminating all such prior art complicated, costly valve blocks and passageways. The only fluid paths in this invention are the pinch tubes themselves, hence failures relating to sliding seals or diaphragms are eliminated in the illustrated form. Complete service and disassembly can be accomplished without tools due to the economical snap fit injection parts.
Although the controls illustrated are used for "high" pressure air, water, other liquids, gases, mixtures and slurries (carrying particulates) may be dispensed under positive or negative pressure in any pressure range consistent with available tubing technology for medical or industrial purposes. These fluids may begin to flow upon removal of the handpiece from the holder, or may be regulated by other interlock valves using pinch tubes or other valves, remotely controlled by foot actuators.
In the apparatus described in U.S. Pat. No. 3,755,899, each dental handpiece is supported in a holder on a pivotally mounted arm, and each arm includes a pinch block at one end which pinches a corresponding flexible tube to prevent the flow of fluid to the handpiece when the holder is in its down position, but which permits the flow of fluid through the tube to the selected handpiece when the holder is in its up position. Therefore, when the dentist selects a particular handpiece from the console, he flips the corresponding holder to its up position, and the handpiece immediately becomes activated, or is remotely activated by foot operated valves or regulators in series with the selected handpiece.
The control unit of the present invention, as described above, like the apparatus described in U.S. Pat. No. 4,117,861 achieves the desired valving effect merely by inserting the handpiece into or removing the handpiece from the corresponding holder. In the present control unit, such action causes the handpiece to engage the actuator so that the holder is firmly and positively moved to a down position in which the flexible tube or tubes are pinched; and then by removing the handpiece from the holder to cause the air and/or water flow path to be directed to the selected handpiece.
The control unit of the present invention, like the control unit of U.S. Pat. No. 4,117,861, is less complex than the prior art control units, as described above. Accordingly, it is relatively inexpensive in that it can be produced and sold at a fraction of the cost of the prior art consoles of the same general type. In addition, the control unit of the invention is easy and convenient to operate, and it does not require any action on the part of the dentist, except to remove a desired handpiece from its holder in the console.